A motor vehicle may be provided with an all-wheel-drive (AWD) powertrain capable of transmitting power to the wheels of a primary axle and to the wheels of a secondary axle. Power is provided to the secondary axle through a rear drive unit having a differential assembly. Various differential assemblies may be utilized, including open, limited slip, and locking differentials. Open differentials have a gear train that allows the output shafts of the differential to spin at different speeds while maintaining the sum of their speeds proportional to the input of the differential, but the amount of torque transferred to the inner and outer wheels must be equal. A limited slip differential allows different amounts of torque to be transferred to the inner-wheel compared to the outer-wheel during a turn.
AWD systems tend to degrade vehicle fuel economy due to increased driveline parasitic losses even when AWD is not activated. These parasitic losses occur, in part, because the secondary drive wheels and their rotation cause a drag torque to be exerted on the driving element. An AWD vehicle may be provided with a driveline disconnect system that improves fuel economy by disconnecting parts of the driveline when AWD is not activated. In many aspects, this is accomplished with a side mounted clutch on a rear drive unit that functions as a torque transfer/disconnect device. In many instances, inclusion of a driveline disconnect system in a side clutch rear drive unit precludes the use of a mechanical limited slip differential in the rear drive unit.